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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Method for repair of thin glass coatings

A method of repairing cracks or damaged areas in glass, in particular, glass coatings provided on tile. The method includes removing the damaged area using a high speed diamond burr drilling out a cavity that extends slightly into the base material of the tile. All loose material is then cleaned from the drilled out cavity and the cavity is filled adjacent the upper surface of the coating with a filler material including chopped silica fibers mixed with a binder. The filler material is packed into the cavity and a repair coating is applied by means of a brush or sprayed thereover. The repair includes borosilicate suspended in solution. Heat is applied at approximately 2100 F. for approximately five minutes for curing the coating, causing boron silicide particles of the coating to oxidize forming a very fluid boron-oxide rich glass which reacts with the other frits to form an impervious, highly refractory layer.

Holt, J. W.↗
NASA NTRS1983

Evaluation of Production Version of the NASA Improved Inorganic-Organic Separator

The technology of an inorganic-organic (I/O) separator, which demonstrated improved flexibility, reduced cost, production feasibility and improved cycle life was developed. Substrates to replace asbestos and waterbased separator coatings to replace the solvent based coatings were investigated. An improved fuel cell grade asbestos sheet was developed and a large scale production capability for the solvent based I/O separator was demonstrated. A cellulose based substrate and a nonwoven polypropylene fiber substrate were evaluated as replacements for the asbestos. Both the cellulose and polypropylene substrates were coated with solvent based and water based coatings to produce a modified I/O separator. The solvent based coatings were modified to produce aqueous separator coatings with acceptable separator properties. A single ply fuel cell grade asbestos with a binder (BTA) was produced. It has shown to be an acceptable substrate for the solvent and water based separator coatings, an acceptable absorber for alkaline cells, and an acceptable matrix for alkaline fuel cells. The original solvent based separator (K19W1), using asbestos as a substrate, was prepared.

Sheibley, D.↗
NASA NTRS1982

Plasma-sprayed self-lubricating coatings

One of the most important criterion for acceptable commercial application of a multiple phase composition is uniformity and reproducibility. This means that the performance characteristics of the coat - e.g., its lubricating properties, bond strength to the substrate, and thermal properties - can be readily predicted to give a desired performance. The improvement of uniformity and reproducibility of the coats, the oxidation behavior at three temperature ranges, the effect of bond coat and the effect of preheat treatment as measured by adhesive strength tests, coating examination procedures, and physical property measurements were studied. The following modifications improved the uniformity and reproducibility: (1) changes and closer control in the particle size range of the raw materials used, (2) increasing the binder content from 3.2% to 4.1% (dried weight), and (3) analytical processing procedures using step by step checking to assure consistency.

Nakamura, H. H.↗
NASA NTRS1982

A compliant, high failure strain, fibre-reinforced glass-matrix composite

A glass-matrix composite reinforced by discontinuous graphite fibers was produced by hot pressing glass-powder-impregnated two-dimensional arrays of in-plane randomly oriented graphite fibers held together by approximately 5-10% by weight of organic binder (generally polyester). The composite tensile behavior is characterized by a highly nonlinear stress-strain curve which differs markedly from that of either unreinforced glass or a similarly reinforced epoxy-matrix composite. By virtue of this nonlinearity, the composite is able to redistribute applied stresses to achieve a high load-carrying capacity. The fibrous microstructure and the low fiber-matrix bond provide a mechanism for achieving high fracture toughness and unusually high compliance. For a 96%-silica-matrix composite, the strength is retained to over 1000 C.

Prewo, K. M.↗
NASA NTRS1982

Improved uniformity of multiphase ceramic-metal plasma-sprayed coats

Processing-technology development of a multiphase, self-lubricating, plasma-spray powder resulted in greater uniformity and reproducibility of plasma-sprayed coats. The effect of particle-size variation, binder concentration, and reproducible processing parameters are reported. Greater adhesive strengths of coats to substrates were achieved by particle-size variation, use of an intermediate bond coat such as Ni-Cr, or heat treatment. Quantitative analyses of polished, coated specimens are also given.

Nakamura, H. H.↗
NASA NTRS1985

High-Temperature Coating for Titanium

Wet coating mixture composed of graphite pigment potassium silicate binder solution and distilled water. Resulting coating has electrical resistivity of less than 10 to the 6th power ohm-cm.

Mell, R. J.↗
NASA NTRS1983

Method of manufacturing ceramic shaped articles

A method of manufacturing ceramic shaped articles, wherein tapes of ceramic powder material in mixture with a binder material and special additives are shaped and then articles are stamped out from said tapes and sintered in a sintering furnace is described.

Inoue, K.↗
NASA NTRS1983

Electrodes for solid state devices

The invention relates to coated metal powders and to dispersions of such powders in liquid vehicles forming screenable, sinterable pastes for use in forming electrodes on photovoltaic devices. The primary nickel or copper metal particles are provided with a carrier of lower melting sintering metals such as 1-20% by weight, of a non-oxidizing metal such as lead or tin. The powdered metal systems operate on the basis of fusing together by way of eutectic alloying. As the paste is heated during firing the organic binder is first vaporized. An eutectic of the base metal (copper) and coating (tin) forms at the intersections of the base metal grains. This eutectic dissolves the grains and as the temperature is raised above the eutectic temperature, more of the base metal is dissolved. While the temperature is held at the higher value, the much smaller amount of sintering metal disappears as the eutectic dissolves and diffuses into the base metal until the composition of the eutectic is so enriched with base metal that it no longer has the eutectic properties and it solidifies. In this high temperature solidification, the base metal grains became thoroughly alloyed together and will not separate at the eutectic temperature (a lower temperature than their solidification by diffusion).

Bickler, D. B.↗
NASA NTRS1984

Diamondlike flake composites

A carbon coating is vacuum arc deposited on a smooth surface of a target which is simultaneously ion beam sputtered. The bombarding ions have sufficient energy to create diamond bonds. Spalling occurs as the carbon deposit thickens. The resulting diamond-like carbon flakes are mixed with a binder or matrix material to form a composite material having improved thermal, electrical, mechanical, and tribological properties when used in aerospace structures and components.

Banks, B. A.↗
NASA NTRS1984

Organic materials for ceramic molding processes

Ceramic molding processes are examined. Binders, wetting agents, lubricants, plasticizers, surface active agents, dispersants, etc., for pressing, rubber pressing, sip casting, injection casting, taping, extrusion, etc., are described, together with forming machines.

Saito, K.↗
NASA NTRS1983

Rigid closed-cell polyimide foams for aircraft applications and foam-in-place technology

Significant accomplishments generated are summarized. Testing of closed cell foams, which has resulted in the characterization of compositions which produce rigid foams for use in galley structure applications is reported. It is shown that the density, compressive strength and shear strength of the foams are directly related to the concentrations of the microballoons. The same properties are also directly related to the resin loading. Prototype samples of rigid closed cell foams meeting the requirements of the program were submitted. Investigation of the apparatus to produce polyimide foams using foam in place techniques, resulted in the selection of a spray gun apparatus, capable to deliver a mixture of microballoons and resin binder on substrates which cures to yield a closed cell foam. It is found that the adhesion of the foam on aluminum, titanium and steel substrates is satisfactory. It is concluded that the material meets the mechanical and thermal requirements of the program.

Gagliani, J.↗
NASA NTRS1984

LEO atomic oxygen effects on spacecraft materials: STS-5 results

Effects of low Earth orbit (LEO) atomic oxygen were measured on a variety of spacecraft materials which obtained exposure on STS-5. Material degradation dependency on temperature was found in one material. Of the five paints flown, only S13GLO was unaffected. Generally, the glossy paints became Lambertian and the diffuse coatings improved. Scanning electron microscope examinations indicated removal of urethane and epoxy paint binder materials. Reaction products were evident on the surfaces of Z302 paint and Mylar. Thin films showed thickness losses ranging from negligible loss in Teflon to considerable loss in Mylar and Kapton. Glossy films such as black Kapton and white Tedlar became diffused. Kevlar 29 rope lost tensile strength and silver solar cell interconnect material oxidized. Oxidation on the backside of an elevated specimen indicated that reflections of oxygen atoms were occurring and that reflecting surfaces, probably Kapton, were not fully accommodating the incident atoms.

Whitaker, A. F.↗
NASA NTRS1984

Magnetic record support

The magnetic layer of a magnetic record support is coated with a thin film of a polymer with a siloxane bond. The magnetic layer consists of a thin film obtained by vacuum metallization, cathode sputtering or dispersion of a ferromagnetic metal powder in a binder. The polymer with a siloxane bond is produced by the polymerization of an organic silicon compound which inherently contains or is able to form this bond. Polymerization is preferably performed by plasma polymerization.

Nakayama, M.↗
NASA NTRS1984

The direct effects of strain on burning rates of composite solid propellants

A mathematical model is developed to predict burn rate augmentation due to strain in a composite solid propellant. The model assumes the effect is due to the ability of the flame to penetrate the small fissures and voids that form when a propellant is strained. The number and size of these fissures is obtained by applying a flaw propagation analysis to randomly distributed flaws that form when the binder-oxidizer particle bonds break under stress. A flame height is calculated with Summerfield's burn rate equation and is used to compute the burn rate augmentation based upon the additional burn area created when the flame penetrates the fissures. Comparisons are made with data obtained from published sources. The existence of threshold pressure and strains, above which augmentation occurs, is verified although the model predicts a lower threshold pressure and higher threshold strain than expected. Further results and applications of the model are discussed.

Langhenry, M. T.↗
NASA NTRS1986

Improved Surface of Titanium Structure

Potential tooling pickup not acceptable on sandwich panels that have face sheets 0.016 in. (0.41 mm) thick. In this application, problem eliminated by changing tooling slipsheet from type 321 CRES to type 430 stainless steel and coating both slipsheet and face sheet with boron nitride powder and binder thinned in acetone.

Ecklund, R. C.↗
NASA NTRS1984

Injection molding of silicon carbide capable of being sintered without pressure

The most suitable SiC mass for injection molding of SiC articles (for subsequent pressureless sintering) consisted of beta SiC 84, a wax mixture 8, and polyethylene or polystyrene 8 parts. The most effective method for adding the binders was by dissolving them in a solvent and subsequent evaporation. The sequence of component addition was significant, and all parameters were optimized together rather than individually.

Muller-Zell, A.↗
NASA NTRS1985

Diffusely reflecting paints including polytetrafluoroethylene and method of manufacture

The invention pertains to a high diffuse, reflective paint comprising an alcohol soluble binder, polytetrafluoroethylene (TFE) and an alcohol for coating a substrate and forming an optical reference with a superior Lambertian characteristic. A method for making the paint by first mixing the biner and alcohol, and thereafter by mixing in outgassed TFE is described. A wetting agent may be employed to aid the mixing process.

Schutt, J. B.↗